.3 V-5v Charge Pump Step-up Semiconductor Led Lighting Light Source Driver Chip

The energy crisis, caused by rapid economic development, brings about the use of energy conservation technology as the government and people's hot topic. The semiconductor lighting LED with high efficiency, energy conservation, environmental protection, long-lifetime, easy maintenance, is expected to become a new lighting source after the incandescent lamp and fluorescent lamp. Its average annual growth rate of the global market is more than 20%. Our national Semiconductor lighting project was in full swing in 2003. White LED has entered the illumination market with the support of the government, and will promote comprehensively during "11.5" plan.The research of white-LED driving chip has great practical significance.This lighting driving chip in this thesis belongs to boost charge pump type. When the power supply voltage (lithium batteries ) drops to 2.7-3.3V, the output voltage of this chip can be doubled to approximately 5 V with 300mA current.This charge pump includes oscillator, bandgap reference, resistance-feedback network, comparator, data selector, level-shifter, soft-start as well as four power MOS switches. The key problem of the design is the reasonable choice of charge pump's operating frequency, MOSFET switches' W/L, transmission capacitance and the timing control. The charge pump can operate with soft-start and pulse-skip mode(when output voltage is more than 5V, the oscillator stops surging) to reduce the power loss.Also digital logic control units is used to avoid the burr and reverse current during the switch cutting. Control the big MOSFET's substrate always equal to the higher end voltage between the source and drain to prevent pn forwardly bias.This paper comprises five chapters. Chapter I is briefed on the development and driven approach of white LED;Chapter II says the charge pump's types and operating principles;Chapter III is expounded the circuit design of this charge pump;Chapter IV will introduce the chip test and its characteristic analysis;Chapter V is the summary and some improvements vision.The current research on charge pump is in close connection with the development of market dynamics, and can drive for miner's lamp, flashlight, reading lamp, etc., of 1W LED.Its design principles can also be used to promote to higher power led driven.